1. Field of the Invention
The present invention relates to aquarium filtration systems, and more particularly to external aquarium filtration systems with a removable filter cartridges.
2. Background
External aquarium filters pull water from the aquarium tank and pass the water through various physical, chemical, and biological filters. Mechanical filtering typically uses a floss material or the like to screen and remove solid waste material and debris. Chemical filtration reduces ammonia levels using carbon (charcoal) or zeolite. Biological filtration reduces harmful levels of undesirable bacteria using thermoplastic tubules for aerobic bacterial growth. These filtration systems and biological filtration in particular, are improved by increasing the amount of time the water remains in contact with the filtration medium. This time is referred to as “dwell time.”
Conventional filters that use removable/disposable filter cartridges, such as that available with the commercially available Whisper Power Filter or the Marineland Penguin Filter, typically are only able to put the water to be cleaned through a relatively thin layer of cartridge with carbon held within the cartridge. The amount of dwell time of the water within the cartridge in contact with the filter material is therefore limited. In contrast, the AquaClear filter manufactured by the Hagen Corporation, which does not use cartridges, brings water to be filtered from the bottom of the filter through a sponge layer and then through a bag of carbon or other filter material. The water rises up from the bottom of the filter and, under pressure, overflows back into the tank. While this design advantageously increases dwell time, it does so at the expense of the user's convenience. Compared with cartridge filters, this design requires substantial more time and inconvenience to change filter material.
A need, therefore, exists for a filtration system that both provides the convenience of a disposable cartridge filtration system and the improved performance of a system that has an improved dwell time.